From The Scientist:
New data show that protein research is stuck on a small set of molecules that was hot in the 1990s
At the dawn of the 21st century, scientists completed the first draft of the human genome and reported that human cells encode more than 20,000 proteins. But most of the protein research performed since has focused on about 2,000 proteins (mostly enzymes) that were already known and whose functions were well studied, according to an analysis published this week in Nature.
Why do you think researchers are less likely to study previously unexplored systems? The first reason is that scientists are sometimes just like dogs with a bone: They just love their problems. And they love going deeper and deeper, and it's the richness and the complexity of their problem that drives them.
The other thing is that you can get funding for proteins for which there's a preexisting community. The third thing is that when you rationalize your grant, we get rewarded for the elegance for which we weave a tale. You need to have context. When you go to publish a paper, if you work on an unknown protein, you're less likely to capture the imagination of the peer reviewers and they'll probably ask for a lot more work. To study an unknown protein, it takes longer, and that's what nobody has in this modern world -- time.
And then the last thing is research tools. There is no molecular biologist now who would not prefer to use a genome wide knockdown set of RNAis, for example, as opposed to the single RNAi. That's a better experiment, but no such tools exist for proteins. If you have a new protein, you have to make a knockout cell, you have to make an antibody, an inhibitor or mutant. It's a lot of work to create the infrastructure to even do the experiment.